Fix participations for likes on comments in the backend

When liking a comment, the post also gets a participation, and if all
likes/comments get removed again, the participation also gets removed
again.

The only thing still not working properly is the frontend, but that is
already broken when unliking a post. So it shows an invalids state in
the frontend when unliking the post/comment.

app/assets/javascripts/app/models/like_interactions.js

@@ -44,7 +44,8 @@ app.models.LikeInteractions = Backbone.Model.extend({
     var self = this;
     this.userLike().destroy({
       success: function() {
-        // TODO: If user unlikes a post and the last like of all comments, then set participation to false
+        // TODO: unlike always sets participation to false in the UI, even if there are more participations left
+        //  in the backend (from manually participating, other likes or comments)
         self.post.set({participation: false});
         self.trigger("change");
         self.set({"likes_count": self.get("likes_count") - 1});

app/models/like.rb

@@ -32,7 +32,8 @@ class Like < ApplicationRecord
 
   after_destroy do
     self.parent.update_likes_counter
-    participation = author.participations.find_by(target_id: target.id)
+    participation_target_id = parent.is_a?(Comment) ? parent.commentable.id : parent.id
+    participation = author.participations.find_by(target_id: participation_target_id)
     participation.unparticipate! if participation.present?
   end
 

app/models/user/social_actions.rb

@@ -18,7 +18,9 @@ module User::SocialActions
   end
 
   def like_comment!(target, opts={})
-    Like::Generator.new(self, target).create!(opts)
+    Like::Generator.new(self, target).create!(opts).tap do
+      update_or_create_participation!(target.commentable)
+    end
   end
 
   def participate_in_poll!(target, answer, opts={})

spec/models/like_spec.rb

@@ -12,20 +12,34 @@ describe Like, type: :model do
   end
 
   describe "#destroy" do
-    before do
-      @like = alice.like!(status)
-    end
+    let!(:like) { alice.like!(status) }
 
     it "should delete a participation" do
-      expect { @like.destroy }.to change { Participation.count }.by(-1)
+      expect { like.destroy }.to change { Participation.count }.by(-1)
     end
 
     it "should decrease count participation" do
       alice.comment!(status, "Are you there?")
-      @like.destroy
-      participations = Participation.where(target_id: @like.target_id, author_id: @like.author_id)
+      like.destroy
+      participations = Participation.where(target_id: status.id, author_id: like.author_id)
       expect(participations.first.count).to eq(1)
     end
+
+    context "on comment" do
+      let(:comment) { bob.comment!(status, "Are you there?") }
+      let!(:like) { alice.like_comment!(comment) }
+
+      it "should delete a participation" do
+        expect { like.destroy }.to change { Participation.count }.by(-1)
+      end
+
+      it "should decrease count participation" do
+        alice.comment!(status, "Yes, I am here!")
+        like.destroy
+        participations = Participation.where(target_id: status.id, author_id: like.author_id)
+        expect(participations.first.count).to eq(1)
+      end
+    end
   end
 
   describe "counter cache" do